Accurate control of engine air/fuel ratio requires knowledge of the quantity of fresh air drawn into the engine cylinders -in each engine cycle. Ordinarily, this can be determined either by sensing the mass air flow in the intake manifold of the engine or through a computation involving the engine speed and a measure of the manifold absolute pressure. The fuel pulse width so determined can then be adjusted to account for other factors that influence the air charge. With variable cam phase engines, for example, the phase angle of the cam must be taken into account since changing the cam angle changes the degree of overlap between the cylinder intake and exhaust valves. One way of compensating for the variable cam phasing is to simply measure the actual cam position, and adjust the fuel pulse width to account for the corresponding degree of valve overlap. However, in transient operation, the cam phase continues to change in the interval between fuel pulse width computation and the corresponding combustion cycle, resulting in fueling errors that adversely affect emissions. Accordingly, what is needed is a fuel compensation method that more accurately accounts for the air charge changes due to cam phase angle, even during transient operation.